Assessment and classification of lignocellulosic biomass recalcitrance by principal components analysis based on thermogravimetry and infrared spectroscopy

Lignocellulosic biomass is a high potential feedstock to produce biofuels and value-added products contributing to sustainable bioeconomy. Nevertheless, biomass recalcitrance reduces the yield of processing routes, and therefore, characterization of structural and chemical factors contributing to this resistance must be carried out by robust but rapid and economical analytical techniques. In this work, the recalcitrance of eight lignocellulosic biomass samples: agave bagasse (AB), banana peel (BP), corn cob (CB), barley straw (BS), orange peel (OP), pineapple peel (PP), sugarcane bagasse (SB) and sawdust (SW), was performed infrared spectroscopy and thermogravimetric analysis. The classification of chemical and thermal behavior was based on principal components analysis (PCA) by similarity to four reference materials, cotton fiber (CF), lignin (LG), citrus pectin (CP) and potato starch (PS). The results indicate a clear trend of recalcitrance in four well-defined groups (GPI-GPIV): GPII or lignin-like biomasses (LG and AB) were assessed as the most recalcitrant biomass type (devolatilization temperature: similar to 150 degrees C, remaining weights > 30wt%), followed by GPI or cellulosic-like biomass (CF, SW and SB), which contain high amounts of cellulose that increase its recalcitrance to thermal degradation (devolatilization temperature: 200-380 degrees C, remaining weights < 20wt%). GPIII or pectin-like biomasses (CP, PP, OP, BP), known to be significant sources of pectin and hydrolyzable polysaccharides, were classified as intermediated recalcitrance biomasses (devolatilization temperature: 150-350 degrees C, remaining weights < 30%wt,), whereas GPIV or starchy-like biomasses (PS, BS and CB) were the least recalcitrant materials (devolatilization temperature: 250-350 degrees C, remaining weights < 30 wt%). This methodology could be applied to classify novel uncharacterized lignocellulosic biomasses irrespectively of their origin based on their similarity to reference materials and to preselect the processing route, to biofuels or biomaterials, in a fast and economical manner. Graphic

Automated summary

This study investigated the recalcitrance of eight lignocellulosic biomass samples through spectroscopy and thermogravimetric analysis, identifying four distinct resistance trends that can classify uncharacterized lignocellulosic biomasses.